I'll pick him up and put him back and bed and he'll stop the rest of the night. Is he having anxiety?
I had a guest dog do this. Given all the other anxiety related behavior I witnessed with him, I assume his 3 am wake up calls were also stress-induced. As for how to stop it.. maybe he'd be more comfortable with his bed closer to where you're sleeping?
He may just want reassurance that all is well, especially if he heard or smelled something. Sometimes guests pups in a new environment do this.
My dog does this occasionally but we are super connected so I can figure out what she wants most of the time. It's not like her to wake up in the middle of the night so I know something is wrong. Usually it's because she needs to go potty, she is telling me her stomach is upset. Other times she is cold and wants to cuddle. It has never been anxiety but more of her telling me she needs something.
It seems to help after I pick him up and put him next to me in my bed. He sleeps with me though.